DE69814764T2 - Process and device for waste processing under supercritical conditions - Google Patents

Description

The present invention relates to a processing method and processing device for organic scraps and a processing method and a processing device for inorganic Waste.

In recent years, the Disposal of organic waste, including Resins such as B. plastic containers or polyvinyl chloride or radioactive materials to a big problem. conventional become the organic waste disposed of by incineration, however, in such a processing method Problems arise in that dangerous materials, such as. B. dioxin, nitrogen oxides and the like are generated and reclamation this dangerous Materials a great Facility is required.

They also contain inorganic scraps in the field of nuclear energy in addition to radioactive materials a big Volume of sodium nitrate. Consequently, radioactive materials with sodium nitrate as a solidified body in an underground located processing area stored. As a result of a current Study of the underground environment is reported to be the underground has a low partial pressure of oxygen, which makes it likely is that nitrate ions are converted to ammonia. That is why indicated that there is a likelihood that radioactive Material such as plutonium and the like complex with ammonia forms and is washed out of the solidified body.

Recently has as a method of decomposing an organic material Procedure attracted attention when using water high temperature and high pressure (supercritical water) and at which the critical point of water (temperature: 374 ° C, pressure: 22.1 MPa) is exceeded.

The supercritical state referred to a state of a substance at one temperature and one There is pressure, which is the critical temperature and the critical Exceed pressure, which are physical quantities that the individual Connections inherent are and a substance in this state is called supercritical Designated fluid.

A method is known for which is an organic material and a fluid, the water and oxygen contains are mixed, and the organic material at a super critical Condition that exceeds the critical point of water oxidizes / decomposes ("procedure for the oxidation of organic materials in water, which is supercritical Point exceeds ", Japanese patent application No.Sho-56-68414, registered under number 1551862). The supercritical Water, the properties of which are between the properties of a liquid and a gas and that with an organic material and can be mixed with oxygen in any ratio can effectively decompose the organic material in a short time.

Occurs in the supercritical state however a problem arises in that the inorganic materials, those in organic waste are included on the surface of the reactor fail, which clogs the reactor because the solubility inorganic materials is very small. Because the solubility of the inorganic oxides is particularly small, it is likely that such difficulties are caused.

For example, if the waste is one Nuclear power plant being processed is more radioactive due to the failure Materials not easy to handle and maintenance of the waste processing device is very expensive.

Therefore the development of a Process and an apparatus for decomposing organic waste under Use of the supercritical Condition without failures inorganic substances expected.

Furthermore, if ammonia in a solidified body as described above, there is a probability that radioactive materials such. B. plutonium from the solidified body be washed out. Hence the development of a waste processing method and a device expected even if the waste that include only inorganic materials that are processed by Convert the nitrate ions or nitrate salts to nitrogen Exclude content of nitrate ions in the solidified body.

From the above it can be seen that the present invention was made to solve the problems of usual Technology to solve. The object of the present invention is to provide a Process and an apparatus that organic waste or inorganic waste can decompose effectively in a short time.

In a first aspect, the present invention provides a waste processing method comprising a step of decomposing all or almost all of the organic matter contained in organic waste into lower molecular weight products by keeping the organic waste in a medium, which is in a supercritical state and in the absence of an oxidizing agent for a predetermined period of time and comprises a step of oxidizing and decomposing the lower molecular weight products to carbon dioxide (CO ₂ ) and / or water (H ₂ O) by holding a mixture of an oxidizing agent and the lower molecular weight products in the medium which is in a supercritical state for a predetermined period of time.

According to this procedure, after the decomposition of an organic substance into products with lower Molecular weight in supercritical Water in the absence of an oxidizer is the organic substance oxidized to subcritical water by adding the oxidizing agent and decomposes in which the inorganic substances hardly precipitate. Therefore, the organic matter can be effectively decomposed and it prevents the inorganic substance from precipitating.

Non-limiting examples of organic scraps are paper, waste, Activated carbon, asphalt and various types of resins. The organic scraps can Contain nitrate, sulfate, chloride, phosphate, silicate or mixtures thereof.

The organic waste can be insoluble materials, such as B. include sand, gravel, pebbles and the like.

Some of the resins also contain such as B. polyethylene, polypropylene, PET resin and various types of ion exchange resins no inorganic additive or organic Additive and other resins such as B. polyvinyl chloride, silicone, fiber-reinforced plastic (FRP) and the like contain an inorganic additive and / or an organome tallow salt additive.

Examples of the inorganic additives are stabilizers, such as. B. lead salts or tin salts, fillers such. B. CaCO ₃ or SiO ₂ , flame retardants such. B. Al ₂ (OH) ₃ , Sb ₂ O ₃ , MgO and carbon for imparting conductivity or for reinforcement. Pencil stearate is an example of the organometallic salt additive.

If the organic waste is one size Amount of impurities, inorganic additives or organometallic salt additives, then the amount of waste, which is processed per unit of time, preferably reduced, so that a failure of the inorganic substances is prevented.

Preferably the method comprises the step of separating insoluble impurities contained in the organic wastes prior to the oxidation and decomposition of the lower molecular weight products to carbon dioxide (CO ₂ ) and / or water (H ₂ O).

According to this preferred method the organic substance can be effectively decomposed even then if the organic waste described above is a size Amount of insoluble Contain impurities, inorganic additives or organometallic salt additives, while a failure of the inorganic substance in the subcritical Medium can be prevented because the failed insoluble contaminants after the supercritical Processing removed and then the organic substance through the addition of an oxidizing agent oxidizes in subcritical water and is decomposed. Therefore, the amount of processing need not be reduced become.

In these waste processing methods, it is preferable to set the hydrogen ion concentration of the medium to 10 ^-4 mol or more per 1 kg of the medium. This improves the solubility of the inorganic substance, which further reduces the precipitation of the inorganic substance.

Water, Carbon dioxide, a hydrocarbon or mixtures thereof are used become.

In general, substances that are at room temperature and atmospheric pressure in the gas phase or the liquid Are present in a medium in a supercritical state in one any ratio uniform be mixed. Furthermore can be compared in the supercritical medium with a liquid Medium a higher Mass transfer speed to be expected. Therefore, as a supercritical Medium of the present invention considering the processed Water, carbon dioxide and hydrocarbons are used which all have the properties described above. About that by mixing these media, their critical point can be changed.

At least as an oxidizing agent the stoichiometric Amount of oxygen, air, hydrogen peroxide, ozone or mixtures of which used to complete Oxidation of organic waste is required. 1.2 to 10 times the stoichiometric amount is more prefers.

For setting the hydrogen ion concentration an inorganic acid is preferably used, and in particular sulfuric acid or hydrochloric acid. For example, however, an acid (e.g. nitric acid) that pyrolyzed at a high temperature, suitably not used.

The second aspect of the present invention provides a waste processing apparatus comprising a decomposition reactor for decomposing all or almost all of the organic matter in organic waste to lower molecular weight products in a supercritical medium in the absence of an oxidizing agent, the decomposition reactor being an organic waste feeder, provides feed means for the medium and means for forming a supercritical state in the reactor, the decomposition reactor having no means for feeding an oxidizing agent, an oxidation reactor for oxidizing and decomposing the lower molecular weight organic product into a fluid, the carbon dioxide and / or Contains water in a subcritical state, the oxidation reactor providing means for feeding the lower mole products molecular weight generated in the decomposition reactor, supply means for an oxidizing agent and a means for forming the subcritical state in the second reactor, and recovery means for recovering the fluid generated in the second reactor, the recovery means comprising a gas-liquid - Separating device for separating the fluid into a gas and a liquid, a gas processing device for processing the gas and a liquid processing device for processing the liquid, wherein the liquid processing device further comprises a solidification device ( 46 ) for solidifying the liquid / sludge.

The above processing device can with a feeder for neutral salts be equipped, the medium that are fed to the reactor should add a neutral salt.

The reactor can be equipped with one device for irradiation of ultraviolet rays or radiation or Radial jets on the contents of the reactor.

The liquid processing device can with a neutralizing device to neutralize a in the liquid contained acid be equipped.

The device preferably comprises furthermore an adjusting device for adjusting the hydrogen concentration in the decomposition reactor (if both a decomposition and a an oxidation reactor is provided) or the reactor for the device according to the third Aspect of the invention. The setting device can be designed in this way be that a medium by adding an inorganic acid a predetermined hydrogen ion concentration is set and fed to the reactor becomes.

The setting device can be designed in this way be an acid feeder to feed an inorganic acid to the reactor, a hydrogen ion concentration measuring device for measuring the hydrogen ion concentration in the reactor and a control device for feeding a calculated amount of the inorganic acid from the acid supply device to the reactor based on a signal from the hydrogen ion concentration measuring device having.

It is preferred that as inorganic Acid at least an acid is used, which is selected from sulfuric acid and hydrochloric acid.

By providing an oxidant delivery device to feed an oxidizer to the reactor can be the adjuster be designed so that the hydrogen ion concentration according to the species of organic waste or inorganic waste and the feed amount of Oxidizing agent is set. The different types of scraps can can be processed with excellent efficiency.

The waste processing device according to the invention for the Reactor can be insoluble with a separation device for separation Impurities that are contained in organic waste or in inorganic waste are included.

It is preferred to set up one for detecting a state of a medium in the reactor, to be able to evaluate correctly whether the medium in the reactor is supercritical Condition is present or not, so the waste is under the optimal conditions are processed. If, for example, a device in the reactor is arranged to measure the temperature and pressure, then the state of the medium can be recorded. Instead of direct measurement the temperature and pressure within the reactor can Temperature and pressure of a mixture of the medium and the waste the feeder be measured to the reactor.

For the feeder for the organic waste or the inorganic waste and for the medium feed device can be a pressurizing device for pressurizing the organic waste or inorganic waste and the medium with pressure and a preheating device for preheating of organic waste or inorganic waste to be provided. For the recovery device can a pressure reducing device for decompressing the fluids generated in the reactor and cooling means for cooling the same to be provided. If an acid supply device or Oxidant feeder are present, then a pressurizing device can be used for pressurizing the acid or the oxidant with pressure and a preheater be arranged for preheating the same. With such a structure Processing can be improved efficiently since the waste and the like continuously fed / recovered and can be processed.

The preferred oxidizing agent is 1 times or more, preferably 1.2 to 10 times the stoichiometric Amount of oxygen, air, hydrogen peroxide or their mixtures used to complete Oxidation of organic waste or inorganic waste is required.

A covering device can preferably be used to cover at least a part of the feed device for the organic Waste or the inorganic waste can be arranged. For example can contain at least part of the organic waste or the inorganic scraps preferably arranged in a glove box or a hood his.

The cover device is preferred explosion resistant.

The recovery device includes a gas-liquid separation device, a gas processing device and a liquid processing device.

It is further preferred that the Gas processing device comprises a filter that has a solid component, a radioactive material or a dangerous substance in the gas removed, as well as a washer, which is a radioactive material or a dangerous substance in the liquid recovers.

It is also used as a solution in the scrubber is used, at least one substance consisting of water, one alkaline solution, which contains sodium hydroxide or water containing a reducing agent is selected.

The liquid processing device preferably comprises a device for taking a liquid sample and to analyze the liquid.

It is preferred that the liquid processing device a device for stirring the liquid having.

The liquid processing device preferably comprises a device for cooling the liquid.

The liquid processing device preferably comprises a device for aggregating and precipitating inorganic Ions in the liquid.

The liquid processing device preferably has a means for collecting a solid component in the liquid on.

The liquid processing device preferably has an ion exchange device for removal one in the liquid contained ionic component.

The liquid processing device preferably has an extraction / recovery device Extracting / recovering inorganic ions in the liquid on, by enabling that the liquid is in contact with an extractant.

The preferred extractant is at least one substance used, which consists of a neutral organophosphorus compound or an acidic organophosphorus compound is selected.

As a diluent for the extractant carbon dioxide is preferably used.

The liquid processing device preferably comprises a drying device for drying Liquid / sludge.

The liquid processing device comprises a solidification device for solidifying liquid / sludge.

It is preferred that the solidification device in a container a mixture of a liquid, a sludge, or a mixture thereof and a solidifying agent solidified.

According to the invention during processing organic waste or inorganic waste using a medium in the supercritical state, the precipitation of inorganic Substances in organic waste or inorganic waste are effectively prevented. Therefore, a large volume of waste be processed effectively and the design effort for the equipment or the Operating costs can can be drastically reduced.

1 Fig. 11 is a flowchart showing a waste processing method of the embodiment according to the present invention 1 shows;

2 Fig. 11 is a flowchart showing a conventional waste processing method;

3 Fig. 12 is a graph showing the solubility of lead oxide in the supercritical and subcritical states;

4 Fig. 12 is a graph showing changes in the ionic product of water when the temperature and pressure are varied;

5 Fig. 12 is a graph showing the precipitation (%) of cerium when the amount of the oxidizing agent is varied;

6 12 is a schematic diagram showing a waste processing device of the embodiment 2 shows;

7 Fig. 12 is a schematic diagram showing a separator disposed on the lower part of a reactor;

8th Figure 12 is a curve showing the critical curves of water and hydrocarbon mixtures;

9 Fig. 11 is a schematic diagram showing a waste processing apparatus of Example 2 useful for understanding the invention;

10 12 is a schematic diagram showing a waste processing device of the embodiment 3 shows;

11 Fig. 12 is a schematic diagram showing a waste processing apparatus of Example 3 useful for understanding the invention;

12 12 is a schematic diagram showing a waste processing device of the embodiment 4 shows;

13 Fig. 10 is a schematic diagram showing an alpha-radiation radionuclide recovery device of the embodiment 4 shows;

14 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 5 shows;

15 Fig. 12 is a graph showing a phase diagram of water;

16 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 6 shows;

17 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 7 shows;

18 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 8th shows;

19 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 9 shows;

20 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 10 shows;

21 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 11 shows;

22 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 12 shows;

23 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 13 shows;

24 Fig. 12 is a schematic diagram showing part of a waste processing apparatus of the embodiment 14 shows;

25 Fig. 12 is a graph showing the distribution ratio of actinides in a 30% TBP nitric acid system; and

26 Fig. 10 is a graph showing the distribution ratio of actinides in a system made of HDEHP nitric acid.

Various other tasks, advantages and features of the present invention will become apparent from the following detailed description clearly and the new features will be especially in the attached claims shown.

In the following embodiments or the following description of the embodiments will be the same Elements designated by the same reference numerals, whereby a multiple description is excluded.

Embodiment 1

1 Fig. 11 is a flowchart showing a waste processing method of the embodiment 1 of the present invention. 2 Fig. 11 is a flowchart showing a conventional waste processing method.

Like it in 2 is shown, according to the conventional method, in one step for producing a supercritical medium 1 Water, which is the medium, made supercritical. In one step 2 organic waste containing sulfate is added to the water in the supercritical state. The mixture thus obtained is in a decomposition step 6 held together with an oxidizing agent for a predetermined period of time at high temperature and high pressure, which exceed the critical point of the water. The organic waste comprising sulfate is oxidized and decomposed in the supercritical water.

The decomposition gas and the decomposition liquid and the inorganic substances such as. B. sulfate contained in the organic waste becomes a recovery step 5 transferred, and z. B. subjected to solidification processing after the recovery of a dangerous material.

According to the method of the embodiment 1 the water becomes the medium in the step of making the supercritical medium 1 heated to a supercritical state and pressurized. In the mixing step 2 organic wastes comprising sulfate are added to the supercritical water thus obtained. Instead of mixing the supercritical medium with organic waste, after mixing the medium and the organic waste, the medium can be made supercritical by heating and applying pressure.

In a partial decomposition step 3 the resulting mixture, which contains no oxidizing agent, is kept in the supercritical water for a predetermined period of time, whereby all or almost all of the organic materials contained in the sulfate-containing organic wastes are decomposed to lower molecular weight products.

The lower molecular weight products produced in step 3 are then subjected to a decomposition / oxidation step 4 mixed with an oxidizing agent and kept in a subcritical state for a predetermined period of time.

The decomposition gas thus generated and the decomposition liquid and the inorganic material (ions) such. B. the sulfate contained in the organic waste becomes the recovery step 5 transferred and after the recovery of dangerous materials such. B. subjected to solidification processing.

In the conventional method, the in organic waste contained organic materials effectively decomposed by oxidation become. If in organic waste, however, inorganic materials are present, then the inorganic materials form in the supercritical State compared to the subcritical state of light oxides and fall out.

An explanation is given below with lead as an example. 3 is a graph showing the solubility of lead oxide under supercritical and subcritical conditions (Chemical Engineering Society, 63rd Annual Meeting, Tohoku University, Engineering Faculty, Sue et al. "Solubility measurement of metal oxides in subcritical and supercritical water"). The solubility of lead oxide in a supercritical range of 374 ° C or more is low. For example, the solubility at 450 ° C is 0.5 × 10 ^-3 mol / kg or more. In a subcritical range, however, the solubility increases to 0.5 × 10 ^-2 mol / kg, that is to say approximately 10 times the value of the supercritical range. The solubility tends to decrease with the simultaneous presence of oxygen.

Therefore, if organic waste that comprise an inorganic additive or an organometallic salt additive, like the conventional one Case in the presence of an oxidizing agent in a supercritical Processed state, then the inorganic materials fall, those in the inorganic additive or the organometallic salt additive are contained as oxides.

Because in the partial decomposition step 3 there is no oxidizing agent, in this embodiment the inorganic materials, such as. B. sulfate contained in the organic wastes are not oxidized, and thereby the inorganic oxides are prevented from precipitating.

After that, the organic materials by adding an oxidizing agent in a subcritical Condition is effectively oxidized and decomposed (step 4).

If the organic materials in the supercritical React water before oxidation by adding an oxidizing agent are left, bonds with a low binding energy selectively pyrolyzed or hydrolyzed in the organic materials, so the organic high molecular weight materials too Lower molecular weight products are decomposed. Then the organic materials that have been converted to lower molecular weight products an oxidizing agent is added in a subcritical state. In such a case, the organic materials react due to their lower molecular weight quickly with oxygen, thereby the for the time required for oxidation is greatly reduced.

Therefore, by keeping the organic scraps in a subcritical state for a predetermined period of time after keeping the organic waste in a supercritical Condition for effectively decomposed and oxidized for a predetermined period of time, while the failures of inorganic materials is prevented.

Although in the embodiment 1 Hydrogen peroxide is used as an oxidizing agent, other materials can be used instead, such as. B. oxygen, air, ozone or mixtures thereof.

The organic materials are generally decomposes when they react with radicals. The hydroxy radical (·OH: hereinafter referred to as OH radical) is special compared to the organic materials active. The OH radical demonstrates this in Equation I in an acidic solution 25 ° C shown Oxidation reduction potential and is used as an oxidizing agent used that stronger is as ozone.

OH · + H ⁺ + e ^- → H ₂ O 2.85V against NHE (1) In order to effectively decompose organic materials, the generation of OH radicals is therefore an important key feature.

If water in a supercritical State and oxygen react, then the OH radical and the hydroperoxide radical (· O OH) as shown in Equation II.

H ₂ O + O ₂ → HO ₂ + OH · (11)

According to the Baulch et al. is the reaction rate constant of the equation II at 500 ° C only 10 ^-10.5 mol / s (oxygen: 0.00631 mol, water: 6.31 mol). Further, the hydroperoxide radical reacts as shown in Equation III, generating hydrogen peroxide and oxygen, and the resulting hydrogen peroxide is further decomposed to generate the OH radical according to Equation IV. HO ₂ + HO ₂ → H ₂ O ₂ + O ₂ (III) H ₂ O ₂ → 2 OH (IV)

Generally the reaction is between the radicals themselves quickly, the decomposition reaction of the Hydrogen peroxide easily takes place at a temperature of 100 ° C or more. Hence the reaction rate of Equations III and IV high.

If an organic in the supercritical water Substance is decomposed in the presence of oxygen, then the Response of equation II to the rate-determining step. If the OH radical is therefore directly by adding hydrogen peroxide is generated, the decomposition reaction of the organic substance take place effectively.

The following was polyethylene according to the method of the embodiment 1 decomposed.

A reactor (5.6 ml) was 10 mg of polyethylene to which 2 mg of Ce adhered in the form of cerium sulfate, and 2 ml of water was added and there was reaction at one temperature of 400 ° C and a pressure of 30 MPa for 30 minutes.

After returning the system to room temperature and atmospheric pressure were 99% or more of the polyethylene that was originally a solid, to alkanes and alkenes (C = 1 to 30) and were in the gas phase or the liquid Phase before.

0.3 g of hydrogen peroxide and 1.6 g of water (3.6 g in total) were added to the reaction product and kept at a temperature of 350 ° C. and a pressure of 30 MPa for 30 minutes. After the reaction, the system was returned to room temperature and atmospheric pressure, and then the organic carbon content in the gas phase and the liquid phase was measured, whereby 99% or more of the organic materials were found to be oxidized and decomposed to CO ₂ and H ₂ O. had been.

The decomposition liquid was filtered and the cerium content in the filtrate was determined by means of ICP (inductively coupled Plasma spectroscopy). Furthermore, after the dissolution of the Filters in an acid the cerium content using ICP in the same way as Measured above, whereby no precipitate was found. consequently all of the cerium was in the form of ions and was not as an oxide failed.

For comparison, polyethylene was used in Presence of an oxidant in the conventional manner in the supercritical Water decomposes.

10 mg polyethylene, on which 2 mg Ce adhered in the form of cerium sulfate, 2 ml of water and 0.3 g of hydrogen peroxide were added to a reactor (5.6 ml) and the resulting mixture was 30 minutes at a temperature of 400 ° C under a pressure of 30 MPa reacted calmly.

As a result, 99% or more of polyethylene is oxidized and decomposed to carbon dioxide and water. The half the cerium precipitated as an oxide.

From the above it can be seen that according to the procedure the embodiment 1 organic waste without failures of the inorganic materials were effectively decomposed.

Example 1 that for understanding the Invention useful is

According to the method of the first example, which is useful for understanding the invention, the conventional step of manufacturing the supercritical medium 1 who in 2 water to which an inorganic acid has been added to adjust the hydrogen ion concentration to 10 ^-4 mol / kg or more is made supercritical and used as a supercritical medium in the subsequent step.

According to Smith et al. becomes a metallic Element in a nitric acid waste liquid and at high temperature and pressure according to the equation V hydrolyzed and then according to the equation VI pyrolyzed, eventually converting it to the oxide becomes.

Since the nitric acid produced according to equation V is pyrolyzed to generate NO _x gas and oxygen, the oxide is easily formed. M (NO ₃ ) _n + n H ₂ O → M (OH) _n + n HNO ₃ (V) M (OH) _n → MO _m (VI)

To prevent such hydrolysis the equation of equation V must also be added by adding a Acid on the left side will be moved.

The hydrogen ion concentration of the water is closely related to the ion product of the water. In 4 the ionic product of water with temperature and pressure is shown as variables.

For example, the ionic product of water at a pressure of 25 MPa at about 300 ° C has the largest value of 10 ^-11 (mol / kg) ² . Therefore, the hydrogen ion concentration of the supercritical water without the presence of an acid and the like is 3.3 × 10 ^-6 mol / kg. Further, under the conditions of the supercritical water at 374 ° C or more, the ionic product of the water becomes less than 10 ^-11 (mol / kg) ² , and is especially 10 ^-24 (mol / kg) ² at 600 ° C. Therefore, the hydrogen ion concentration at 600 ° C reaches an extremely small value of 10 ^-12 mol / kg compared to the hydrogen ion concentration at 300 ° C.

In the conventional case of decomposition the organic materials with the supercritical water are conditions high temperature and relatively low pressure (e.g. 600 ° C, 25 MPa) preferred. Therefore, if the organic materials, the inorganic Include materials only with water at a high temperature be reacted, the hydrogen ion concentration extremely small in the reactor, the equilibrium of equation V becomes shifted to the right side, causing precipitation of the leads inorganic materials as oxides.

In order to increase the ion concentration in the supercritical water, the ion product has to increase. Like it in 4 is shown, the ion product tends to increase with increasing pressure. However, the actually applicable pressure is 50 MPa or less.

For example, the ion product at 350 ° C. and 50 MPa is 10 ^-12 (mol / kg) ² , which is 10 ^-14 (mol / kg) ² 100 times larger compared to the ion product at room temperature and atmospheric pressure. However, the hydrogen ion concentration is around 10 ^-6 mol / kg. It is therefore impossible to greatly increase the hydrogen ion concentration in the supercritical water by selecting the temperature and the pressure. Therefore, in this embodiment, the hydrogen ion concentration is adjusted by adding an acid to the supercritical water so as to prevent the precipitation of oxides.

With the procedure of this example, that for understanding of the invention useful the conditions for preventing precipitation of the Oxides by adding an acid to the supercritical water examined.

In order to adjust the hydrogen ion concentration of the water to 10 ^-4 mol / kg, 5 × 10 ^-5 mol / kg sulfuric acid were added to the water.

The medium and cerium nitrate thus obtained (1 mg based on cerium) were mixed and 30 minutes at 400 ° C, 25 MPa reacted calmly. After the implementation, the system was at room temperature and atmospheric pressure returned and subsequently became the decomposition liquid filtered. The cerium content in the filtrate was measured by ICP. Furthermore, the filter paper was dissolved in an acid and the cer content was raised measured accordingly with ICP to determine the presence of precipitation to rate. The results are shown in Table 1.

Further, as conventional examples, the result given by using only water containing no sulfuric acid as a medium and the result obtained by using a medium containing 5 × 10 ^-6 mol of sulfuric acid, namely 5 × 10 ^{- 5} mol as hydrogen ion concentration per 1 kg of water.

As can be seen from Table 1, in contrast to the conventional examples in which 100% of cerium precipitated as cerium oxide, the precipitation rate became 0% and all of the cerium remained in a dissolved state in the liquid phase when 5 × 10 ^-5 mol Sulfuric acid were added. If 5 × 10 ^-6 mol of sulfuric acid are added, 70% of the cerium precipitates.

From the above, it can be seen that when the acid was added to adjust the hydrogen ion concentration to 10 ^-4 mol / kg, the cerium did not precipitate out.

Table 1

An inorganic material becomes Oxide oxidizes when there is oxygen. In the procedure of this example the conditions were examined in which an organic material without the precipitation of an inorganic material can be decomposed itself when the medium contains an oxidizing agent.

5 shows the results when water, sulfuric acid and an oxidizing agent cerium nitrate (1 mg based on cerium) were added and then reacted at 400 ° C and 30 MPa for 30 min. The ordinate indicates the percentage of the precipitated cerium and the abscissa shows the amount of oxidant added as a multiple of the stoichiometric value.

5 × 10 ^-3 mol of sulfuric acid were added to 1 kg of water. When measured using ICP, it was found that the percentage of cerium precipitation increased with increasing addition of oxidizing agent. Especially when the oxidizing agent was added in an amount of 600 times (0.3 g hydrogen peroxide) the stoichiometric value (assuming that cerium converts to ceria), 97% of the cerium precipitated.

So if there is an oxidizer, must be the amount of acid added elevated become when the amount of the oxidizing agent increases.

Table 2 shows the results obtained by adding 4 times the stoichiometric amount of the oxidizing agent to cerium nitrate (1 mg based on cerium) and allowing the resulting mixture to react at 400 ° C, 30 MPa for 30 minutes. When 5 × 10 ^-2 mol / kg of sulfuric acid was added to the water, the rate of precipitation of the cerium was 0%.

It can therefore be seen that in the presence of an oxidizing agent 5 × 10 ^-2 mol of sulfuric acid (as hydrogen ion concentration; 10 ^-1 mol) 1 kg of water must be added.

Table 2

From the above, it can be seen that even if an oxidizing agent is present, an organic material can be decomposed without precipitation of inorganic materials if an acid is added so that the hydrogen ion concentration is 10 ^-1 mol per 1 kg of the medium.

Furthermore, in the process this Examples of cases examined in which salts of inorganic materials by nitrate were different, in which organic waste was included.

To prepare the respective samples, cerium nitrate, sulfate, chloride, phosphate and oxide (1 mg based on cerium) and an oxidizing agent were added in 4 times the stoichiometric value. Water containing 5 × 10 ^-2 mol / kg sulfuric acid was used as the medium. Each mixture of the medium and the sample was reacted at 400 ° C, 30 MPa for 30 minutes.

The results are in Table 3 shown.

In the case of nitrate, sulfate, Chloride and phosphate was determined by measurement using ICP, that the amount of cerium that was present as ions in water was 100%, causing the precipitation rate of the cerium was 0%. Furthermore, 50% of the oxide, originally called Solid was present in the liquid solved, which means that even then an oxide in the liquid phase recovered if the amount of the oxide is small.

Table 3

From the above it can be seen that according to this Example the organic material without precipitation of the inorganic material is not only decomposed if nitrate is contained, but even if it contains sulfate, chloride, phosphate or oxide.

For example, organic waste comprising an oxide of plutonium using the method of this example the organic waste (e.g. tissues, gloves, etc.) contaminated with plutonium are converted to alpha radiation-free waste (i.e. The trash only include elements that do not emit alpha rays) since the Plutonium is recovered in the form of ions in the liquid can be. This allows the processing costs are reduced.

Furthermore, in the process this For example, investigated whether organic wastes without inorganic failures Materials can be processed or not and by use of sulfuric acid and Hydrochloric acid as inorganic acids for setting the hydrogen ion concentration of the medium.

5 × 10 ^-2 mol of sulfuric acid, 1 × 10 ^-1 mol of hydrochloric acid and 1 × 10 ^-1 mol of nitric acid were added to 1 kg of water as media. Cerium nitrate (1 mg based on cerium) and an oxidizing agent in 4 times the stoichiometric value were added to each medium, followed by reaction at 400 ° C., 30 MPa for 30 minutes. The results are shown in Table 4.

When measuring using ICP showed that cerium in the medium containing sulfuric acid and in the medium the hydrochloric acid contained, did not fail.

However, 100% of the cerium was precipitated in the medium containing nitric acid. It is believed that due to pyrolysis at a high temperature in the case of nitric acid, the hydrogen ion concentration was 10 ^-4 mol or less per 1 kg of water, whereby the solubility of the inorganic material decreased, resulting in the precipitation of cerium.

From the above it can be seen that when sulfuric acid or hydrochloric acid as inorganic acid is used, the organic waste without precipitation of inorganic Materials are decomposed.

Table 4

Embodiment 2

6 Fig. 12 is a schematic diagram showing a waste processing device of this embodiment.

A waste processing device of this embodiment has a reactor 11 , which processes organic waste in supercritical water, a feeder 12 for organic waste, which is the organic waste in the reactor 11 supplies a water supply device 13 which water as a medium to the reactor 11 feeds an oxidation reactor 14 who the in the reactor 11 produced organic products with lower molecular weight oxidized and decomposed, an oxidant supply device 15 that the oxidation reactor 14 supplies an oxidizer and a recovery device 30 on which the products from the oxidation reactor 14 recovers.

The recovery device 30 has a gas-liquid separator 33 , a gas processing facility 34 and a liquid processing device 40 on.

The liquid processing device 40 has a drying device or a dryer 45 , the liquid / mud dries and a consolidation device 46 which solidifies the liquid / sludge.

In this embodiment, the reactor 11 and the oxidation reactor 14 arranged separately and connected to each other by a pipe or the like, so that the in the reactor 11 generated products in the oxidation reactor 14 be transferred. The reactor 11 and the oxidation reactor 14 can, however, be designed so that it is a container that is divided into two rooms by a partition plate. If the pressure and temperature can be adjusted appropriately, can be used as a reactor 11 and as an oxide tion reactor 14 a container can also be used.

The processed wastes are not specifically limited to a particular type. With this device can various organic wastes processed, which include a resin and the like, as well those with a radioactive material and the like are contaminated.

When processing organic waste become the insoluble Impurities such as B. include sand, pebbles, or organic waste such as B. a resin, an inorganic additive or an organometallic additive includes, in some cases the precipitation of inorganic materials cannot be prevented, namely not even if the organic substances in the waste in a supercritical Condition decomposed to lower molecular weight substances and then are further decomposed and oxidized in a subcritical state.

In such a case, it is preferable to reduce the amount of organic waste processed in a period. Furthermore, by arranging a separation device 18 at the bottom section of the reactor 11 as it is in 7 is shown, the inorganic materials that have failed in the supercritical state are removed by the use of gravity or inertia. This prevents the precipitation of the inorganic materials in the subcritical state.

In the 7 shown separation device 18 can inside the reactor 11 or between the reactor 11 and the oxidation reactor 14 to be ordered.

In this embodiment, water is considered supercritical Medium used. It can however other media are used, such as e.g. B. carbon dioxide, different types of hydrocarbons or mixtures thereof.

8th is a graph showing the critical curves of mixtures of water and hydrocarbons. The figure shows the critical curves of water, benzene (a), benzene-heavy water (b), water-toluene (c), water-o-xylene (d), water-1,2,5-trimethylbenzene (e), Water cyclobenzene (f), water ethane (g), water n-butane (h), water naphthalene (h), and water biphenyl (i) are shown. The critical point of water is 374 ° C, 22 MPa. For example in the water-benzene system in 8th the critical point can be lowered to 300 ° C or less by mixing two components in a specific ratio. Therefore, if a mixture of two or more of water, carbon dioxide and hydrocarbons is used as the medium, the organic wastes can be processed under milder conditions of lower temperature and pressure while maintaining the supercritical state.

Although in this embodiment Hydrogen peroxide can also be used as an oxidizing agent other oxidizing agents are used, such as oxygen, Air, ozone or mixtures thereof.

Hydrogen peroxide is preferred used because of the use of hydrogen peroxide as an oxidizing agent the organic material can be effectively decomposed.

Furthermore, complete decomposition of the organic material, the amount of hydrogen peroxide added preferably at least the amount necessary to convert the organic scraps in carbon dioxide and / or water is required, and in particular 1.2 to 10 times the crowd.

When processing organic waste with this device, the water supply device 13 Water as a medium to the reactor 11 fed. The reactor 11 , in which the water has been made supercritical, the organic waste is supplied by the feeder 12 for the organic waste, mixed with the supercritical water and kept in a supercritical state for a predetermined period.

The organic waste in the reactor 11 are decomposed into products of lower molecular weight in the supercritical water. The lower molecular weight products are in the oxidation reactor 14 transferred, mixed with the oxidizing agent and kept in a subcritical state so that the products are oxidized to carbon dioxide and water and decomposed.

That in the oxidation reactor 14 generated fluid is in the recovery device 30 transferred to the gas-liquid separator 33 separated into the gas phase and the liquid phase and the resulting gas and liquid are fed into the gas processing device 34 or the liquid processing device 40 transferred to recover hazardous materials.

The solid / liquid phase generated due to the decomposition is after drying in the drying device 45 in a consolidation facility 46 mixed with a solidifying agent, and in a processing container such. B. solidified a drum to form a stable solidified body. Therefore, safety during storage and disposal can be ensured and handling is also simplified. Cement milk, for example, is preferably used as the solidifying agent.

By arranging the feed device 12 for organic waste, the water supply device 13 and the oxidant supply device 15 the organic waste, the water and the oxidizing agent can pass to the reactor 11 continuously fed and with the recovery device 30 the processed products can be removed continuously. Therefore, the organic Waste is processed continuously.

As described above is, can according to the waste processing device this embodiment when processing organic waste using a supercritical Condition the inorganic materials that were previously problematic were before a precipitation be preserved.

Therefore, difficulties such. B. Clogging of the reactor due to the precipitation of inorganic materials can be prevented and the operating costs and maintenance costs the device can thereby be reduced. If the inorganic material further contains radioactive material then an effect in that exposure can be expected of the operating personnel is reduced.

In addition, by Add hydrogen peroxide as an oxidizing agent OH radicals in one generated for a short period of time, creating a large amount of organic substances can be decomposed in a short period of time.

Since the inorganic salts in one ionic form can be recovered without oxide formation and the inorganic substances that are present as an oxide from the start, to some extent in the liquid Recovered phase can be can the organic waste be made homogeneous and uniform.

Example 2 that for understanding the present invention useful is

9 Fig. 12 is a schematic diagram showing a waste processing device of this embodiment.

A waste processing device of Example 2, useful for understanding the invention, has a reactor 11 for processing organic waste in supercritical water, a feed device 12 to supply organic waste, which is the organic waste in the reactor 11 supplies a water supply device 13 who have favored water as a medium to the reactor 11 supplies a pH meter 23 which measures the hydrogen ion concentration in the water in the reactor 11 measures an acid supply device 16 that the reactor 11 supplies an acid to a controller 24 which a calculated amount of an acid to the reactor by controlling the acid feed device 16 based on the value measured by the pH meter 23 and a recovery device 30 for the recovery of products from the reactor 11 on.

The recovery device 30 has a gas-liquid separator 33 , a gas processing facility 34 and a liquid processing device 40 on. The liquid processing device 40 has a dryer 45 , which dries liquid / sludge and a solidification device 46 which solidifies the liquid / sludge.

As acid from the acid supply device 16 an inorganic acid is used, which is ionized in water (medium). An acid that decomposes at a high temperature, such as B. nitric acid, but is not expediently used. Sulfuric acid and hydrochloric acid are preferably used.

As mentioned in Example 1 useful for understanding the invention, precipitation of inorganic substances in the supercritical water can be prevented in the decomposition of the organic wastes when the hydrogen ion concentration of the water is set to 10 ^-4 mol / kg or more becomes.

Depending on the types of organic scraps however, it is necessary to take into account that the hydrogen ion concentration of the water can be influenced by the decomposition product.

When a plastic container made of polyethylene or polyvinyl chloride is kept in the presence of water at a temperature of 374 ° C or more and a pressure of 22.1 MPa or more, the polyethylene is produced to produce an alcohol or an organic one Acid hydrolyzes, while the polyvinyl chloride produces hydrochloric acid in addition to an alcohol or an organic acid. Since the chlorine content in the polyvinyl chloride is 56% by weight, when 0.006 g of polyvinyl chloride is added to 1 kg of water, the hydrogen ion concentration in the reactor is 10 ^-4 mol / kg.

Therefore, if 0.006 g or more of polyvinyl chloride is added to 1 kg of water, an acid addition is not necessary. However, since the polyethylene does not generate any acid, an addition of acid is required when processing polyethylene in order to obtain a hydrogen ion concentration of 10 ^-4 mol / kg.

When waste is decomposed, the polyethylene, that is no acid generated, and include polyvinyl chloride that generates acid, it is by examination the mixing ratio required the amount of acid estimate which is generated from the organic substances.

In this example, the hydrogen ion concentration in the reactor 11 measured directly with the pH meter 23. The control device calculates on the basis of the measured value 24 the amount of acid required to adjust the hydrogen ion concentration to 10 ^-4 mol per 1 kg of water and controls the acid supply device 26 so that the calculated amount of acid goes to the reactor 11 is fed.

With such a system, regardless of the types of organic waste, the hydrogen ions concentration in the reactor are kept in optimal condition.

Furthermore, by feeding the optimal amount of acid according to the species of the waste to be processed the amount of feed Acidity considerable can be reduced.

In addition, a more compact gas-liquid separator can be used for the following reasons 33 than used in the conventional example.

Carbon dioxide is dissolved in water and forms carbonic acid as shown in Equation VII. In water, carbonic acid dissociates into ions, as shown in Equations VIII and IX. CO ₂ + H ₂ O → H ₂ CO ₃ (VII) H ₂ CO ₃ → H ⁺ + HCO ₃ ^- (VIII) HCO ₃ ^- → H ⁺ + (O ₃ ^2- (IX)

In order to shift the equilibrium of equations VII, VIII and IX to the left side of the equations so that carbon dioxide is separated from water, the concentration of hydrogen ions in the aqueous solution must be increased. The acid dissociation constant of equation VIII is 10 ^-3.6 mol / l at 20 ° C. The [HCO ₃ ^- / [H ₂ CO ₃ ] ratios are shown in Table 5 for various hydrogen ion concentrations.

Since H ₂ CO _{3 is} in equilibrium with carbon dioxide in the gas phase, the separation of the carbon dioxide from water becomes difficult when the ratio of HCO ₃ dissolved in the liquid phase to H ₂ CO ₃ becomes larger than 1. In the conventional method, the amount of H ₂ CO ₃ in the liquid is low because the hydrogen ion concentration in the liquid is about 10 ^-7 mol / kg. Consequently, in order to separate water and carbon dioxide, a large amount of air was required to be in contact with the mixture of water and carbon dioxide, which accordingly requires a relatively large gas-liquid separator.

However, since the hydrogen ion concentration is increased to 10 ^-4 mol / kg or more, a gas-liquid separator which is more compact than the conventional separator can be used, thereby reducing the cost of the equipment. Furthermore, the processing volume in the gas processing line can be reduced since the addition of air is not required. As a result, the cost of the equipment and the operating cost can be reduced.

Table 5

Although in this example the hydrogen ion concentration in the reactor 11 When measured directly with the pH meter 23, the arrangement of the pH meter can be difficult in some cases because the inside of the reactor is under a high temperature and a high pressure.

In such a case, after calculating the required amount of acid based on the type and volume of waste to be processed, a mixture of water and the calculated amount of acid can be sent to the reactor 11 are fed.

The hydrogen ion concentration can be controlled without the hydrogen ion concentration to measure the medium in the reactor directly and an arrangement of the pH meter not necessary.

As mentioned above, the hydrogen ion concentration in the processing The organic waste device of this example is controlled by adjusting the supply amount of the inorganic acid according to the types of the organic waste in an optimum state to prevent the inorganic material from falling out. As a result, the processing can be carried out easily even if the wastes contain various kinds of organic materials.

Furthermore, by adjusting the amount of the inorganic acid in water to 10 ^-4 mol or more per 1 kg of water based on the hydrogen ion concentration, the precipitation of inorganic materials can be effectively prevented without much investment in equipment. Furthermore, the gas-liquid separation device can be made compact.

According to this example, the organic waste processed into homogeneous and uniform waste bodies, because the inorganic salts in an ionic form without the formation of Recovered oxides can be and even inorganic materials that have been in one from the start Can be in oxide form in the liquid recovered to a certain extent become.

Embodiment 3

10 12 is a schematic diagram showing a waste processing device of the embodiment 3 shows.

A waste processing device of this embodiment is with the waste processing device of Example 2 , which is useful for understanding the invention, are identical, except that this device is an oxidant delivery device 15 has the oxidizing agent to the reactor 11 supplies.

According to the waste processing device of this example, the organic substances in the reactor 11 made low molecular weight in the supercritical water, and then the pressure and temperature of the water are lowered to a subcritical state, and the lower molecular weight products are oxidized and decomposed into carbon dioxide and water in the subcritical water.

The hydrogen ion concentration in the reactor 11 by controlling the acid feed device 16 by the control device 24 based on the value that is with the pH meter 23 has been measured, adjusted to 10 ^-4 mol per 1 kg of water.

Preferably contain the organic waste not many impurities to be processed, inorganic additions or organic salt additives. If the organic waste a big Volume of inorganic additives and the like, then the amount of organic waste that are to be processed per unit of time can be reduced. There can be a separation device for removing failed substances be arranged so that during the supercritical Processing generated failed substances before the subcritical Processing can be removed.

Consequently, in the processing device for organic scraps this embodiment the inorganic materials due to the oxidation / decomposition in the subcritical state after the organic substances in the supercritical Low molecular weight water has been saved from failure become.

Because the processing in the supercritical State and the subcritical state in the same reactor carried out can be the price for equipment reduced and the operation can be simplified.

Furthermore, by adjusting the hydrogen ion concentration to 10 ^-4 mol per 1 kg of water, the inorganic substances can be effectively prevented from being precipitated.

By adjusting the supply amount of inorganic acid according to Art and the volume of the organic waste and the volume of the oxidizing agent can maintain the hydrogen ion concentration in an optimal state be controlled, even if the wastes are different Contain types of organic substances.

Therefore, difficulties such. B. clogging of the reactor due to inorganic precipitation Materials are prevented, and the operating costs as well Maintenance costs of the device can can be reduced. If the inorganic materials are also a contain radioactive material, the operating personnel can make a reduction of exposure to of radiation.

Furthermore, by adding the Oxidizer a big one Volume of organic materials can be processed in a short time.

Since the inorganic salts in one ionic form recovered without conversion to an oxide form can be and the inorganic materials from the start in an oxide form templates in the liquid Phase recovered to a certain extent can be can the organic waste too homogeneous and uniform waste bodies are processed.

Example 3 that is for understanding the Invention useful is

11 Fig. 12 is a schematic diagram showing a waste processing device of this example.

A waste processing device of this example has the same construction as the device of embodiment 3, but instead of the feeder 12 a feeder for organic waste 51 arranged for inorganic wastes to the reactor 11 feeds inorganic waste, an ammonia processing facility 52 is for the gas processing facility 34 and an alpha nuclide recovery facility 53 is for the liquid processing device 40 provided. Like it in 12 is shown, the alpha nuclide recovery device 53 an aggregation / precipitation device 43 and a separator 44 that separates a solid component from the liquid.

The inorganic wastes can also be arranged without the arrangement of the inorganic waste feeder 51 with the feeder 12 for the organic waste. Since the organic waste and the inorganic waste can be processed with the same equipment, this is preferable in view of the cost.

As material to be processed The trash preferred which comprise only inorganic materials, e.g. B. can solidified body processed, which include alpha-emitting waste. The materials however, are not limited to the above materials and waste which include organic materials can also be processed become.

If the inorganic waste containing a radioactive material such. B. Alpha radiation emitting radionuclides or nitrate, processed with the present device, water is the medium of the reactor 11 with the water supply device 13 fed. Through the feeder 51 for inorganic wastes, the inorganic wastes are added to the water in the reactor 11 has been made supercritical, mixed with the supercritical water and kept in the supercritical state for a predetermined period.

The hydrogen ion concentration in the reactor 11 is set in such a way that, based on the value measured by the pH meter 23, the controller 24 the acid supply device 16 controls so that the sulfuric acid is added to the water so that the hydrogen ion concentration is kept at 10 ^-1 mol per 1 kg of water.

The inorganic wastes are in the supercritical water in the reactor 11 oxidized / decomposed in the presence of the oxidizing agent.

In this example, radioactive materials (e.g., alpha-radiation emitting radionuclides including plutonium and the like) can be recovered in the liquid phase without being precipitated because the hydrogen ion concentration of the water has been adjusted to 10 ^-4 mol / kg , The nitric acid or nitrate in the inorganic wastes can be decomposed without being precipitated and recovered as ammonia in the gas phase.

The fluid generated is sent to the recovery device 30 fed to in the gas-liquid separator 33 to be separated into a gas and a liquid, the gas or the liquid of the gas processing device 34 and the liquid processing device 40 are fed.

In the ammonia processing facility 52 the gas comprising ammonia is heated to 310 ° C or more in the presence of a platinum catalyst to convert the ammonia to nitrogen.

In the aggregation / precipitation facility 43 the alphanuclide recovery facility 53 the liquid which contains the alpha-radiation-emitting radionuclides, such as e.g. B. Plutonium and the like, mixed with barium to form barium sulfate, which is slightly soluble. The alpha-radiation emitting radionuclides with valence III and IV precipitate together with barium sulfate. The alpha-radiation emitting radionuclides of valence V and VI precipitate after being reduced to valence III and IV by a reducing agent together with barium sulfate. If cesium, strontium and the like are contained in the liquid, these can be absorbed by an absorbent such as e.g. B. zeolite, cobalt ferrocyanide and titanium acid can be precipitated together.

If the liquid also contains ammonia, then after adjusting the pH to 9 by adding Sodium hydroxide released the ammonia from the liquid into the gas phase.

The barium sulfate, which comprises the precipitated alpha-radiation emitting radionuclides, is in the separator 44 collected and processed to solidified glass bodies or solidified cement bodies.

In addition to barium, the liquid can to adjust the pH to 4 or more iron, so the alpha radiation emitting radionuclides along with the iron hydroxide produced in this way fail. Together with the iron hydroxide can the alpha rays emitting Radionuclides can be processed to solidified cement bodies. To the Collecting the alpha radiation emitting radionuclides can also a common precipitation performed with lanthanum phosphate become.

The liquid from which the alpha radiation emitting radionuclides have been removed is in the dryer 45 dried, in the consolidation facility 46 mixed with a solidifying agent and solidified in a waste processing container (e.g. a drum) to obtain solidified bodies from non-alpha radiation wastes. As a solidifying agent, for. B. cement milk is preferably used.

As mentioned above, inorganic materials such as. B. A radioactive material and nitrate in the waste processing apparatus of this example can be prevented from precipitation by controlling the hydrogen ion concentration of the medium in the supercritical state to 10 ^-4 mol per 1 kg of water. Therefore, difficulties such. B. blockage of the reactor due to precipitation of the inorganic materials can be prevented and the operating costs and the maintenance costs of the device can be reduced. In addition, a reduction effect of operator exposure can be expected.

According to this example, include the solidified body of alpha-emitting waste no nitrate, as almost all nitrate ions during supercritical processing be decomposed to nitrogen. Therefore, even if the solidified body exposed to a reducing atmosphere underground, no ammonia generated and the radioactive materials such. B. Plutonium can before washing out of the solidified bodies are prevented.

Furthermore, the non-alpha emitter solidified body, by solidifying the liquid / sludge is obtained from which the alpha-radiation emitting Radionuclides have been pretty much removed in one layer shallow depth can be deposited and thus the disposal of the Waste simplified become. This means that the waste deposited in a deep layer can be reduced, resulting in a reduction in disposal costs leads.

If, for example, a solidified vitreous through recovery the alpha radiation emitting radionuclides (e.g. plutonium) from a solidified body is manufactured with conventional Radioactive waste processes is obtained, the volume of the alpha-emitting waste can be considerably reduced become.

According to this example, the Alpha-radiation emitting radionuclides collected through failures. It can but not only the alpha radiation emitting radionuclides, but also inorganic ions, such as. B. Metals in the liquid phase solved are, failed become.

In the waste processing device the embodiment 2, the identical structure can be used.

Embodiment 4

The waste processing apparatus of this embodiment is of the construction with the waste processing apparatus of the embodiment 2 identical, but this device is with a heating device 25a and a compressor 26a for the feeder 12 for organic waste, a heating device 25b and a compressor 26b for the water supply device 13 , a heater 25c and a compressor 26c for the oxidant supply device 15 and a pressure reducing device 31 and a cooling device 32 for the recovery device 30 equipped as it is in 13 is shown.

In the waste processing apparatus of Example 2 or the embodiment 3 can the feeder 12 for organic waste, the water supply device 13 , the oxidant supply device 15 and the acid supply device 16 be equipped with the identical heating devices and compressors and the recovery device 30 can be equipped with the identical pressure reducing device and the identical cooling device.

In the waste processing device of Example 3, the feeder can 51 for inorganic waste, the water supply device 13 , the oxidant supply device 15 and the acid supply device 16 be equipped with the identical heating devices and compressors and the recovery device 30 can be equipped with the identical pressure reducing device and the identical cooling device.

The heaters 25a to 25c heat the organic waste, the medium or the oxidizing agent and the compressors 26a to 26c pressurize the organic waste, the medium or the oxidizing agent. According to such a structure, the organic wastes, water and the oxidizing agent can be continuously fed to the reactor 11 are supplied and the organic waste can be processed continuously without lowering the reaction temperature and the reaction pressure.

The one in the oxidation reactor 14 Decomposition products generated are the recovery device 30 fed and in the pressure reducing device 31 or the cooling device 32 decompressed and chilled. With such a structure, the fluid consisting of the products can continuously flow out of the oxidation reactor 14 are removed and the subsequent gas-liquid separation of the liquid in the gas-liquid separation device 33 can be done effectively.

If the decomposition by adding is carried out from oxygen to an organic substance Carbon is converted to carbon dioxide and hydrogen to water. Under supercritical Water conditions will separate water and carbon dioxide because of the arbitrary Mixing the water, which is the medium, and carbon dioxide, created by the decomposition is difficult. If that fluid formed due to decomposition, however, to room temperature chilled and at atmospheric pressure can be decompressed, most of it of water and carbon dioxide are separated.

Consequently, according to this embodiment, the processing speed can be increased and the operating cost can be greatly reduced compared to conventional batch processing. Furthermore, the gas-liquid separation in the gas-liquid separation device 33 be carried out effectively.

Embodiment 5

The waste processing device of this embodiment is identical to the device of embodiment 2, but this device is with a temperature sensor 21 and a pressure sensor 22 equipped for the reactor as in 14 is shown.

In the waste processing device of the embodiments 3 and 4 the identical structure can be used.

In 15 the phase diagram of water is shown. Since the state of the water is determined by the temperature and pressure, it can be monitored by the temperature and pressure in the reactor 11 be determined whether the inside of the reactor 11 is in a supercritical state or in a subcritical state.

It is preferred to assess whether the medium is in the oxidation reactor 14 is or is not in a subcritical state by providing the temperature sensor and the pressure sensor not only for the reactor 11 , but also inside the oxidation reactor 14 make.

If the device is the heaters 25a to 25c and the compressors 26a to 26c as in the embodiment 7 , then the temperature and pressure of the wastes and the medium being heated and pressurized can be measured prior to being fed into the reactor. The conditions inside the reactor can thereby be estimated without directly measuring the temperature and the pressure inside the reactor.

Embodiment 6

The waste processing device of the embodiment 9 is identical to the device of embodiment 2, but at least part of the reactor is 11 and the feeder 12 for organic waste of this device within a glove box 27 arranged as it is in 16 is shown.

The waste processing devices of the embodiments 3 . 4 or 5 can be constructed in a corresponding manner.

If organic waste that is contaminated by radioactive materials or dangerous substances is processed, then the radioactive materials or dangerous substances must be prevented from escaping to the outside. According to the waste processing device of the embodiment 3 almost all processing steps are carried out in a closed system. However, due to the inclusion of the organic waste, the feeder 12 for organic waste partly to an open system. Therefore, when processing organic waste contaminated by radioactive materials or hazardous substances, the spread of contamination must be arranged by arranging the feeder 12 for organic waste within a cover element, such as. B. a trigger or a glove box can be prevented.

It is further preferred that the Cover element, such as. B. the trigger or the glove box according to one explosion-proof specification. Therefore, the processing performed even then be when volatile organic substances that tend to explode during the Decomposition of organic waste generated or if volatile organic substances that tend to explode on the organic waste be liable.

According to this embodiment can be the yardstick the equipment compared to the case where the entire device is within of the cover member is made smaller because part of the processing device inside the glove box is arranged.

Embodiment 7

The waste processing device of the embodiment 7 is identical to the device of embodiment 2, but this device is with a feed device 29 equipped for neutral salt to add a neutral salt to the water, which is the medium, as in 17 is shown.

In the waste processing device of the embodiments 3 to 6 an appropriate structure can be used.

In general, the solubility product Ks of a salt M _n L _m that is sparingly soluble is expressed using the activity as equation X. M ^{m + n} + L → M _n L _m, Ks = a ₁ a ₂ ^m · ⁿ (X) a ₁ : activity of M ^{m +} , a ₂ : activity of L ^n-

The activity a is expressed as equation XI with an activity coefficient γ and a concentration C. a = γ · C (XI)

When the temperature and pressure are fixed, the activity is also fixed and Ks has a fixed value accordingly. In a dilute solution where γ = 1, activity a becomes identical to concentration C. However, as the ionic strength increases, γ becomes γ <1, which leads to an increase in the concentration C, and the dissolved ions M ^{m +} and L ^n- in the solution increase, increasing the solubility.

Therefore if a neutral salt is added solubility decreases of the slightly soluble Salt too, resulting in oppression the precipitation leads.

As a neutral salt is preferred Sodium chloride, potassium chloride, calcium chloride, magnesium chloride, Sodium sulfate and potassium sulfate are used.

According to this embodiment the addition of a neutral salt can precipitate the inorganic substance can be suppressed more effectively.

Embodiment 8

The waste processing device of the embodiment 8th is identical to the device of embodiment 2, but this device is with an irradiation device 28 equipped, which can irradiate radiation rays on the contents of the reactor, as it is in 18 is shown.

In the waste processing device of the embodiments 3 to 7 the identical structure can be used.

Instead of an irradiation device a UV radiation device that emits UV rays, be used.

When irradiation rays are irradiated on water, an OH radical is generated as shown in the following equation XII. H ₂ O → H + OH · (XII)

The OH radical is a powerful oxidizer, as shown in equation I, which eliminates the organic substances can be decomposed without the use of an oxidizing agent.

Furthermore, if the UV rays or the radiation rays are irradiated in the presence of an oxidizing agent, this reaction can be further accelerated. For example, oxygen generates radicals due to the radiation and eventually hydrogen peroxide. The hydrogen peroxide reacts according to the following equation XIII by the radiation to generate the OH radical, which leads to the decomposition of the organic substances. H ₂ O ₂ + hν → 2 OH (XIII)

Ozone reacts with UV rays according to the following equation XIV to produce hydrogen peroxide. Furthermore, the hydrogen peroxide reacts with the UV rays according to equation XIII to generate the OH radical. O ₃ + H ₂ O + hν → H ₂ O ₂ + O ₂ (XIV)

Furthermore, the hydrogen atom generated according to equation XII reacts with oxygen according to equation XV to generate the hydroperoxide radical, the hydroperoxide radical reacting with ozone according to equation XVI and the generation of the OH radical. H + O ₂ → HO ₂ · (XV) O ₃ + HO ₂ → OH + 2O ₂ (XVI)

Therefore, due to radiation the OH radical can be generated more effectively, making the organic Substance is effectively decomposed.

If the waste, which is the radioactive Include material, be processed without an external radiation source the radiation field can be easily generated. consequently the effect described above can be done without an irradiation device be preserved.

Embodiment 9

The waste processing device of the embodiment 9 is with the device of the embodiment 2 identical, but this device is with a filter 25 that removes a solid component or a dangerous component contained in the gas phase and with a washer 26 equipped to remove dangerous substances contained in the gas phase, as described in 19 is shown.

The identical structure may be in the waste processing device of the embodiments 3 to 8th be used.

For example, when processing waste that are contaminated by radioactive materials that have been generated by a reprocessing plant, then go volatile Elements such as B. technetium and ruthenium in the gas phase.

Ruthenium changes into the gas phase as ruthenium tetraoxide. However, if an organic substance is present, then ruthenium tetraoxide is reduced to ruthenium dioxide (RuO ₂ ). Since ruthenium dioxide is in solid form at room temperature, it can be removed by a filter.

Technetium is also converted to ditechnetium heptoxide or pertechnetic acid and goes into the gas phase. However, when technetium is in contact with water, as shown in Equations XVII and XVIII, it is dissolved in water in an ionic form. Tc ₂ O ₇ (g) + H ₂ O → 2 HTcO ₄ (g) (XVII) HTcO ₄ (g) → TcO ₄ ^- + H ⁺ (XVIII)

Therefore, if a washer is arranged, can Technetium in a liquid recovered become.

To the elements such. B. Technetium and to recover it more effectively, it is preferred for the washer an alkaline solution other than water that includes sodium hydroxide, or use water that includes a reducing agent.

When technetium comes in contact with water is, then solve it is in the form of negative ions, as described in equations XVII and XVIII is shown. Because the negative ions through the reaction Generate a salt with sodium ions Salt in the solution recovered become.

Technetium will also if there is a reducing agent from pertechnetic acid (VII-valent) reduced to technetium dioxide (IV-valuable). Because the solubility of technetium dioxide in water at room temperature and atmospheric pressure is low, technetium can be recovered in a solid form in water become.

Consequently, according to this embodiment solid components or volatile dangerous Elements that move into the gas phase due to entrainment removed, and those contaminated with radioactive materials scraps can processed safely.

Embodiment 10

The waste processing device of the embodiment 10 is with the device of the embodiment 2 identical, but the liquid processing device of this device is with a stirrer 41 for stirring the liquid and a sampling / analysis device 42 equipped for sampling / analysis of the liquid as described in 20 is shown.

A corresponding structure can be in the waste processing device of the embodiments 3 to 9 be used.

If that of the gas-liquid separator 33 to the liquid processing device 34 transferred liquid through the stirrer 41 is stirred, the liquid phase can be made uniform. If through the sampling / analysis facility 42 If a part of the uniformly made liquid is sampled and analyzed, the composition of the total liquid phase can be estimated and in the solidification device 46 a solidifying agent can be selected that is best suited for storage and processing. Furthermore, since the content of the solidified body becomes clear, the storage and processing can be made easier.

Even if a solid suspension is contained in the liquid, it can be agitated due to stirring 41 be made uniform, thereby solidifying processing in the solidifying device 35 is simplified.

If the sampling / analysis facility 41 is not arranged, then a means of measuring the content is necessary in view of the implementation, since the content of the solidified body is not clear. However, the measurement of the solidified body content is not accurate because sampling the representative sample is difficult, which leads to a performance problem.

Embodiment 11

The waste processing device of the embodiment 11 is with the device of the embodiment 2 identical, but the liquid processing device is 34 this device with a neutralization processing device 46 equipped, which neutralizes acids and alkaline substances contained in the liquid, as in 21 is shown.

The identical structure can be applied to the waste processing device of the embodiments 3 to 10 can be applied.

For example, when processing radioactive solid waste that include technetium, the technetium becomes ditechnetium heptoxide converted and released into the gas phase.

However, if after recovery of the decomposition products in the recovery facility 30 from the oxidation reactor 14 an alkaline compound, such as. B. sodium hydroxide in the neutralization processing facility 46 added as shown in Equation XIX, technetium, which remains to a small extent in the liquid after gas-liquid separation, can be stabilized in the liquid phase.

Consequently, the solidification processing according to this embodiment can be easily carried out in the solidification device because the dangerous Substance, such as B. a radioactive material in the liquid can be stabilized.

Embodiment 12

The waste processing device of the embodiment 12 is with the device of the embodiment 2 identical, but this device is with a cooling device 47 for cooling the liquid phase in the liquid processing device 34 equipped as it is in 22 is shown.

A corresponding structure can be applied to the waste processing device of the embodiments 3 to 11 be applied.

If radioactive waste is processed without cooling, the liquid will boil easily due to the heat of the radioactive materials in the liquid processing facility 30 , As a result, contamination of the radioactive material is likely to spread. If the liquid with the cooler 47 such a risk can be excluded and the radioactive material can be safely kept in the liquid phase.

Embodiment 13

The waste processing device of the embodiment 13 is with the device of the embodiment 2 identical, but the liquid processing device is 34 this device with an ion exchange tower 48 equipped as it is in 23 is shown.

A corresponding structure can be applied to the waste processing device of the embodiments 3 to 12 be applied.

For example, when processing waste that are contaminated by a radioactive material that volatile elements are produced by a reprocessing plant like technetium and ruthenium into the gas phase. Part of it remains however in the liquid Phase and the technetium and ruthenium are in the liquid as pertechnetic acid and ruthenium chloride complexes or as ruthenium nitrosyl nitrate complexes in front.

The pertechnetic acid, which is an anion, can be used with an anion exchanger Resin can be removed and the ruthenium, which is a cation, can be removed with a cation exchange resin.

Accordingly, according to this embodiment the remaining solution released from the system to the outside be because the dangerous ionic components, such as. B. the radioactive materials that in the solution of the decomposition products contained can be removed, whereby the processing costs of the waste can be reduced accordingly.

Furthermore, as a result of the removal the dangerous ionic component in the liquid the liquid Phase and the solid phase in the waste liquid feed from the Liquid processing line uniform and homogeneous to the solidification device. By clogging of the solidifying agent to this waste liquid can be done with a simple procedure uniform and homogeneous solidified bodies are obtained, i.e. it can solidified body be obtained for a storage and for processing are stable.

Embodiment 14

The waste processing device of the embodiment 14 is with the device of the embodiment 2 identical, but the liquid processing device is 34 Before this device with an extraction / recovery device 49 equipped, which converts dangerous inorganic ions in the water into an extracting agent, through the contact of the liquid with the extracting agent, as described in 24 is shown.

A corresponding structure can be in the waste processing device of the embodiments 3 to 12 be used.

For example, in the radioactive waste produced by a reprocessing plant, nuclear fuel substances like uranium and plutonium. Organic waste containing these elements contained, then, when solidified, become alpha-radiating waste and the processing costs of the solidified bodies increase accordingly. consequently have to these items from the waste be removed.

An extracting agent can be a neutral organophosphorus compound, such as. B. Tributyl phosphate (below referred to as TBP) and an acidic organophosphorus compound, such as z. B. dihexylphosphoric acid (HDEHP) can be used.

In 25 the distribution coefficients of the actinides are shown in a 30 volume% TBP nitric acid system. If the nitric acid concentration is 3 mol / l, the partition coefficients of uranium, plutonium and neptunium are more than 10 and the partition coefficients of thorium are more than 3.

When the liquid to be recovered in the liquid processing device, after which its acid concentration by the extraction / recovery device 49 is set to 3 mol / l, is brought into contact with TBP, then the actinides, such as. B. Plutonium can be recovered in TBP. Furthermore, if the TBP, the actinides such. B. Plutonium is brought into contact with a dilute acid, the actinides, such as. B. Plutonium can be recovered in the dilute acid.

In 26 the distribution coefficients of the actinides are shown using HDEHP. Even if the nitric acid concentration is below 10 ^-1 mol / l, the partition coefficients of plutonium, uranium and americium are more than 100 and consequently they can be recovered in HDEHP. Furthermore, if an acid with a concentration of about 1 mol / l, which is a reducing agent such. B. hydrazine, is brought into contact with HDEHP, then VI-valent plutonium or uranium is reduced to III-valent plutonium or uranium and recovered in the acid.

When the HDEHP is used, the amount of acid added to a separation / recovery device can be reduced because the actinides compared to the case where a neutral organophosphorus compound such as e.g. B. TBP is used to be recovered at an acid concentration of about 10 ^-1 mol / l, whereby the operating costs can be reduced.

As a diluent of the extractant, such as B. the TBP or HDEHP described above, is preferably supercritical Carbon dioxide used to make up the volume of organic used solvent reduce, resulting in a reduction in processing costs of the Secondary waste leads.

The specific density of TBP at Room temperature and atmospheric pressure is about 1 g / ml, i.e. the density is identical to the density of water, whereby by means of an addition of n-dodecane as a diluent to TBP the organic phase and the water phase easily separated can be. If to recover a radioactive material such as B. Plutonium TBP and n-dodecane are used then they become radioactive and they have to be considered radioactive organic waste are processed.

Since generally the mixing ratio of TBP to n-dodecane is about 30:70 (based on the Volume), the amount of n-dodecane to be processed is more than 2 times the amount of TBP. Therefore, the processing cost can be reduced to 1/3 if the n-dodecane does not have to be processed.

Because carbon dioxide in conditions above 31 ° C, 7.4 MPa into a supercritical Condition passes and mixed with an organic substance in any ratio can be the actinides, such as B. plutonium and the like, in the TBP from the decomposition liquid recovered if the TBP with the supercritical Carbon dioxide is brought into contact. If the carbon dioxide after usage is returned to room temperature and atmospheric pressure, it becomes a gas and can be easily separated from the TBP, whereby the processing of carbon dioxide is accordingly not required is.

Therefore, the processing costs can be drastically reduced if the carbon dioxide is in its supercritical Condition as a diluent is used.

As described above is, can according to this embodiment through recovery the dangerous inorganic ions in the liquid the processing costs of the solidified with the extractant body be reduced.

Furthermore, as a result of the distance the dangerous inorganic ions from the liquid that of the solidification device from the liquid processing device supplied waste liquid in their fluid Phase and in their solid phase uniform and homogeneous. Only by adding a solidifying agent to the waste liquid can uniform and homogeneous solidified bodies are obtained, i.e. with a simple procedure solidified body be obtained for storage and processing are stable.

Claims (19)

A waste processing method comprising a step of decomposing all or almost all of the organic matter contained in organic waste to lower molecular weight products by holding the organic waste in a medium which is in a supercritical state, and in the absence of an oxidant for a predetermined period of time; and a step of oxidizing and decomposing the lower molecular weight products to carbon dioxide (CO ₂ ) and / or water (H ₂ O) by holding a mixture of an oxidizing agent and the lower molecular weight products in the medium that is in is in a supercritical state for a predetermined period of time. A waste processing method according to claim 1, the further comprises a step of separating insoluble impurities, those in organic waste are included. Waste processing method according to claim 1 or 2, in which the organic waste a nitrate, a sulfate, a chloride, a phosphate, a silicate or Mixtures of them included. Waste processing method according to one of the preceding Expectations, where the medium is water, carbon dioxide, a hydrocarbon or Mixtures of it is. Waste processing method according to one of the preceding Expectations, where at least the stoichiometric Value of oxygen, air, hydrogen peroxide, ozone or mixtures of which, for complete oxidation of organic waste is required as an oxidizing agent. A waste processing method according to any preceding claim, wherein the hydrogen ion concentration of the medium which is in a supercritical state is 10 ^-4 mol or more per 1 kg of the medium. A waste processing method according to any one of the preceding claims, wherein by adding at least one of sulfuric acid and hydrochloric acid, the hydrogen ion concentration of the medium which is in a supercritical state is adjusted to 10 ^-4 mol or more per 1 kg of the medium. A waste processing device comprising a decomposition reactor ( 11 ) to decompose all or almost all of the organic substance in organic waste to lower molecular weight products in a supercritical medium in the absence of an oxidizing agent, the decomposition reactor ( 11 ) a feed device 12 for organic waste, a feeder 13 for the medium and a device for forming a supercritical state in the reactor, the decomposition reactor ( 11 ) has no device for supplying an oxidizing agent, an oxidation reactor ( 14 ) for oxidizing and decomposing the lower molecular weight organic product into a fluid containing carbon dioxide and / or water in a subcritical state, the oxidation reactor ( 14 ) means for feeding the lower molecular weight products which are in the decomposition reactor ( 11 ) have been generated, a feed device ( 15 ) for an oxidizing agent and a device for forming the subcritical state in the second reactor ( 14 ) and a recovery device ( 30 ) for recovering the fluid generated in the second reactor, the recovery device ( 30 ) a gas-liquid separation device ( 33 ) for separating the fluid into a gas and a liquid, a gas processing device ( 34 ) for processing the gas and a liquid processing device ( 40 ) for processing the liquid, the liquid processing device further comprising a solidification device ( 46 ) for solidifying the liquid / sludge. A waste processing apparatus according to claim 8, in which the decomposition reactor is a separator for separating insoluble Contains impurities contained in the organic waste are. Waste processing apparatus according to claim 8, at of the feeder for organic Waste, the feeder for the Medium and the feed device for the Oxidizing agent a pressurizing device for pressurizing the organic waste, of the medium or the oxidizing agent with pressure, and a preheating device for preheating the same, and at the recovery device one Decompression device for decompressing a fluid which is in the reactor has been generated, and cooling means for cooling the same having. Waste processing apparatus according to claim 8, which further comprises a device for detecting the conditions of the Medium in the decomposition reactor and the oxidation reactor comprises. Waste processing apparatus according to claim 8, in which the decomposition reactor and the oxidation reactor are furthermore a device for irradiating UV rays or radiation rays on the contents of the decomposition reactor and the oxidation reactor having. A waste processing apparatus according to claim 8, wherein the gas processing device ( 33 ) includes a filter for recovering a solid component, radioactive material or dangerous substance contained in the gas, and a scrubber for recovering the radioactive material and dangerous substance contained in the gas. A waste processing apparatus according to claim 8, wherein the liquid processing device ( 40 ) includes means for aggregating inorganic ions in the liquid so that they fail. A waste processing apparatus according to claim 8, wherein the liquid processing device ( 40 ) comprises means for collecting a solid component in the liquid. A waste processing apparatus according to claim 8, wherein the liquid processing device ( 40 ) comprises an ion exchange device for removing an ion component contained in the liquid. A waste processing apparatus according to claim 8, wherein the liquid processing device ( 40 ) an extraction / recovery device for extracting / recovering inorganic ions contained in the liquid by contacting the liquid with an extractant. A waste processing device according to claim 17, where the carbon oxide as a diluent of the extractant is used. A waste processing apparatus according to claim 8, wherein the decomposition reactor ( 11 ) a facility device for adjusting the hydrogen ion concentration in the decomposition reactor.